U.S. patent application number 16/049992 was filed with the patent office on 2019-10-10 for attaching storage resources to virtual machine instances.
The applicant listed for this patent is INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Stefan Amann, Matthias Lukas Chavanne, Walter Niklaus, Linda-Marie Weber.
Application Number | 20190310873 16/049992 |
Document ID | / |
Family ID | 61965693 |
Filed Date | 2019-10-10 |
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United States Patent
Application |
20190310873 |
Kind Code |
A1 |
Amann; Stefan ; et
al. |
October 10, 2019 |
ATTACHING STORAGE RESOURCES TO VIRTUAL MACHINE INSTANCES
Abstract
A data processing system includes one or more computer systems,
each executing at least one hypervisor. Host bus adapters on the
computer system are connectable to storage resources in at least
one storage area network. The at least one hypervisor provides
virtual instances of the host bus adapters as virtual host bus
adapters, and a world-wide unique port number and a logical unit
number are used to access a storage volume. A globally unique
identifier is used to identify the storage volume. The system
includes a management server comprising a management instance for
evaluating a possibility of attaching storage resources to virtual
machine instances generated by the hypervisor.
Inventors: |
Amann; Stefan; (Boeblingen,
DE) ; Niklaus; Walter; (Jettingen, DE) ;
Weber; Linda-Marie; (Beuerberg, DE) ; Chavanne;
Matthias Lukas; (Stuttgart, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
Armonk |
NY |
US |
|
|
Family ID: |
61965693 |
Appl. No.: |
16/049992 |
Filed: |
July 31, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 2009/45562
20130101; G06F 9/45558 20130101; G06F 2009/45583 20130101; G06F
2009/45579 20130101; G06F 2009/45595 20130101 |
International
Class: |
G06F 9/455 20060101
G06F009/455 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 2018 |
EP |
18165583.8 |
Claims
1. A data processing system for attaching storage resources to
virtual machine instances, the data processing system comprising: a
memory; and a processor in communication with the memory, wherein
the data processing system is configured to perform a method, said
method comprising: obtaining, by a management instance of a
management server, a storage area network request for a group
comprising at least one world-wide unique port number for one or
more virtual host bus adapters, wherein a virtual host bus adapter
is a virtual instance of a host bus adapter of a computer system of
the data processing system, the host bus adapter to couple the
computer system to one or more storage resources of one or more
storage area networks, the at least one world-wide unique port
number to be used to access at least one storage resource of at
least one storage area network; initiating, based on the storage
area network request, discovery for each world-wide unique port
number of the at least one world-wide unique port number in the
group on one or more host bus adapters of the computer system to
collect information; analyzing the information collected to
determine availability of storage resources to attach to one or
more virtual machine instances generated by a hypervisor of the
computer system; and initiating, based on the analyzing,
configuring at least one of virtual host bus adapter to attach one
or more storage resources to at least one virtual machine instance
of the one or more virtual machine instances.
2. The data processing system according to claim 1, wherein the
method further comprises: obtaining a request by the management
instance on each startup of a virtual machine instance in order to
optimize selection of host bus adapters for virtual host bus
adapters of the virtual machine instance; and analyzing the
information collected to determine a best available host bus
adapter in dependence of path quality criteria.
3. The data processing system according to claim 2, wherein the
path quality criteria comprise at least one of path redundancy and
utilization of one or more host bus adapters.
4. The data processing system according to claim 1, wherein the
storage area network request comprises information on storage
requirements, including information on a number and storage size of
storage resources to be requested.
5. The data processing system according to claim 1, wherein the
method further comprises automatically determining when the storage
area network request has been fulfilled.
6. The data processing system according to claim 1, wherein the
initiating discovering comprises triggering a discovery process
through one or more host bus adapters for one or more virtual host
bus adapters of a virtual machine instance.
7. The data processing system according to claim 1, wherein the
method further comprises performing continuous monitoring to
determine changes in availability of a storage resource.
8. The data processing system according to claim 1, wherein the
method further comprises alerting the hypervisor based on
requirements of the storage area network request being fulfilled in
the discovery.
9. The data processing system according to claim 1, wherein the
method further comprises updating the storage area network request
based on information on new virtual host bus adapters being
provided to the management instance.
10. The data processing system according to claim 1, wherein the
method further comprises periodically repeating discovery to update
information on one or more storage resources.
11. The data processing system according to claim 1, wherein the
method further comprises obtaining the storage area network request
by the management instance from the hypervisor before a virtual
machine instance is generated by the hypervisor.
12. A computer program product for attaching storage resources to
virtual machine instances, the computer program product comprising:
a computer readable storage medium readable by a processing circuit
and storing instructions for performing a method comprising:
obtaining, by a management instance of a management server, a
storage area network request for a group comprising at least one
world-wide unique port number for one or more virtual host bus
adapters, wherein a virtual host bus adapter is a virtual instance
of a host bus adapter of a computer system of the data processing
system, the host bus adapter to couple the computer system to one
or more storage resources of one or more storage area networks, the
at least one world-wide unique port number to be used to access at
least one storage resource of at least one storage area network;
initiating, based on the storage area network request, discovery
for each world-wide unique port number of the at least one
world-wide unique port number in the group on one or more host bus
adapters of the computer system to collect information; analyzing
the information collected to determine availability of storage
resources to attach to one or more virtual machine instances
generated by a hypervisor of the computer system; and initiating,
based on the analyzing, configuring of at least one virtual host
bus adapter to attach one or more storage resources to at least one
virtual machine instance of the one or more virtual machine
instances.
13. The computer program product according to claim 12, wherein the
method further comprises: obtaining a request by the management
instance on each startup of a virtual machine instance in order to
optimize selection of host bus adapters for virtual host bus
adapters of the virtual machine instance; and analyzing the
information collected to determine a best available host bus
adapter in dependence of path quality criteria.
14. The computer program product according to claim 12, wherein the
method further comprises performing continuous monitoring to
determine changes in availability of a storage resource.
15. The computer program product according to claim 12, wherein the
method further comprises updating the storage area network request
based on information on new virtual host bus adapters being
provided to the management instance.
16. The computer program product according to claim 12, wherein the
method further comprises periodically repeating discovery to update
information on one or more storage resources.
17. A computer-implemented method of attaching storage resources to
virtual machine instances, the computer-implemented method
comprising: obtaining, by a management instance of a management
server, a storage area network request for a group comprising at
least one world-wide unique port number for one or more virtual
host bus adapters, wherein a virtual host bus adapter is a virtual
instance of a host bus adapter of a computer system of the data
processing system, the host bus adapter to couple the computer
system to one or more storage resources of one or more storage area
networks, the at least one world-wide unique port number to be used
to access at least one storage resource of at least one storage
area network; initiating, based on the storage area network
request, discovery for each world-wide unique port number of the at
least one world-wide unique port number in the group on one or more
host bus adapters of the computer system to collect information;
analyzing the information collected to determine availability of
storage resources to attach to one or more virtual machine
instances generated by a hypervisor of the computer system; and
initiating, based on the analyzing, configuring of at least one
virtual host bus adapter to attach one or more storage resources to
at least one virtual machine instance of the one or more virtual
machine instances.
18. The computer-implemented method according to claim 17, further
comprising: obtaining a request by the management instance on each
startup of a virtual machine instance in order to optimize
selection of host bus adapters for virtual host bus adapters of the
virtual machine instance; and analyzing the information collected
to determine a best available host bus adapter in dependence of
path quality criteria.
19. The computer-implemented method according to claim 17, further
comprising performing continuous monitoring to determine changes in
availability of a storage resource.
20. The computer-implemented method according to claim 17, further
comprising updating the storage area network request based on
information on new virtual host bus adapters being provided to the
management instance.
Description
[0001] This application claims priority from European patent
application number EP18165583.8, filed Apr. 4, 2018, which is
hereby incorporated herein by reference in its entirety.
BACKGROUND
[0002] One or more aspects relate in general, to data processing
systems, and in particular, to attaching storage resources to
virtual machine instances through storage area networks.
[0003] Network port names, also known as world-wide unique port
names (WWPNs), and associated host bus adapters (HBAs), are part of
the IEEE Fibre Channel Standard. Virtualization of Fibre Channel
(FC) network ports allows sharing of physical FC ports by multiple
operating systems by letting each operating system have its own
world-wide unique port names. An operating system may receive
access to logical units (LUN) through a small computer system
interface (SCSI) target port in a storage area network (SAN) by
using one or more WWPNs owned by the operating system. This
capability architecturally allows multiple operating systems to
share a physical FC port. One or multiple FC ports may be hosted on
a single FC adapter. Multiple operating systems may share a server
that has firmware and software capabilities to provide SCSI
input/output (I/O) services to each operating system by
virtualizing physical hardware.
SUMMARY
[0004] Shortcomings of the prior art are overcome and additional
advantages are provided through the provision of a data processing
system for attaching storage resources to virtual machine
instances. The data processing system includes a memory, and a
processor in communication with the memory, and is configured to
perform a method. The method includes obtaining, by a management
instance of a management server, a storage area network request for
a group comprising at least one world-wide unique port number for
one or more virtual host bus adapters. A virtual host bus adapter
is a virtual instance of a host bus adapter of a computer system of
the data processing system. The host bus adapter is to couple the
computer system to one or more storage resources of one or more
area networks. The at least one world-wide unique port number is to
be used to access at least one storage resource of at least one
storage area network. Based on the request, discovery is initiated
for each world-wide unique port number of the at least one
world-wide unique port number in the group on one or more host bus
adapters of the computer system to collect information. The
information collected is analyzed to determine availability of
storage resources to attach to one or more virtual machine
instances generated by a hypervisor of the computer system. Based
on the analyzing, configuring of at least one virtual host bus
adapter to attach one or more storage resources to at least one
virtual machine instance of the one or more virtual machine
instances is initiated (e.g., information is provided to
configure).
[0005] In one embodiment, a request is obtained by the management
instance on each startup of a virtual machine instance in order to
optimize selection of host bus adapters for virtual host bus
adapters of the virtual machine instance. The information collected
is analyzed to determine a best available host bus adapter in
dependence of path quality criteria.
[0006] The path quality criteria include, for instance, at least
one of path redundancy and utilization of one or more host bus
adapters.
[0007] In one example, the storage area network request includes
information on storage requirements, including information on a
number and storage size of storage resources to be requested.
[0008] In one aspect, it is automatically determined when the
storage area network request has been fulfilled.
[0009] Further, the initiating discovering includes, for instance,
triggering a discovery process through one or more host bus
adapters for one or more virtual host bus adapters of a virtual
machine instance.
[0010] In one embodiment, continuous monitoring is performed to
determine changes in availability of a storage resource.
[0011] Further, in one embodiment, the hypervisor is alerted based
on requirements of the storage area network request being fulfilled
in the discovery.
[0012] As an example, the storage area network request is updated
based on information on new virtual host bus adapters being
provided to the management instance.
[0013] Discovery is periodically repeated, in one embodiment, to
update information on one or more storage resources.
[0014] Moreover, in one embodiment, the storage area network
request is obtained by the management instance from the hypervisor
before a virtual machine instance is generated by the
hypervisor.
[0015] Methods and computer program products relating to one or
more aspects are also described and claimed herein.
[0016] Additional features and advantages are realized through the
techniques described herein. Other embodiments and aspects are
described in detail herein and are considered a part of the claimed
aspects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Aspects of the present invention together with the
above-mentioned and other objects and advantages may best be
understood from the following detailed description of the
embodiments, but not restricted to the embodiments.
[0018] FIG. 1 depicts an overview of a network based data
processing system for storage access through virtual host bus
adapters according to an embodiment of the invention;
[0019] FIG. 2 depicts an overview of an implementation of an
embodiment of the invention with a storage request facility for
managing virtual host bus adapters;
[0020] FIG. 3 depicts a flow chart for operating a computer system
according to an embodiment of the invention;
[0021] FIG. 4 depicts a flow chart for a discovery process
according to an embodiment of the invention;
[0022] FIG. 5 depicts a port discovery list, a storage request and
a LUN list as a result of the discovery process according to an
embodiment of the invention;
[0023] FIG. 6 depicts a flow chart for a monitoring process
according to an embodiment of the invention;
[0024] FIG. 7 depicts a port discovery list, a storage request and
a LUN list as a result of the monitoring process according to an
embodiment of the invention; and
[0025] FIG. 8 depicts an example embodiment of a data processing
system for executing a method according to aspects of the
invention.
DETAILED DESCRIPTION
[0026] In the drawings, like elements are referred to with equal
reference numerals. The drawings are merely schematic
representations, not intended to portray specific parameters of
aspects of the invention. Moreover, the drawings are intended to
depict only typical embodiments of the invention, and therefore,
should not be considered as limiting the scope of aspects of the
invention.
[0027] In one or more of the embodiments, a data processing system
is provided that comprises one or more computer systems executing
at least one hypervisor each, wherein host bus adapters on the
computer system are, for example, permanently connectable to
storage resources in at least one storage area network. The at
least one hypervisor provides virtual instances of the host bus
adapters as virtual host bus adapters, and a world-wide unique port
number and a logical unit number are used to access a storage
volume. The storage volume is identified, for instance, by its
globally unique identifier (GUID).
[0028] The embodiments are sometimes described herein using
particular technologies only as an example for the clarity of the
description. The embodiments are used, as an example, for a data
processing system characterized by a management server comprising a
management instance for evaluating a possibility of attaching
storage resources to virtual machine instances generated by the
hypervisor. The management instance handles storage area network
requests for a group comprising at least one world-wide unique port
number for a virtual host bus adapter. In response of such a
request, a discovery is performed for each world-wide unique port
number in the group on each host bus adapter for virtual host bus
adapters and the collected information is then analyzed to
determine the availability of the corresponding storage
resources.
[0029] A Fibre Channel protocol (FCP, SCSI over Fibre-Channel)
provides for a very robust, fast, and scalable storage attachment.
It is very commonly used in high-end server configurations and
prevents the creation and allocation of storage resources from
becoming cumbersome, and error-prone, particularly, for instance,
when environments scale to tens, or hundreds of virtual
servers.
[0030] The Fibre Channel standard is based upon world-wide unique
port names (WWPNs) which are used for identifying virtual host bus
adapters on the server side, and on the storage subsystem side.
These WWPNs are, e.g., 16 hex-digit numbers. Server administration
and SAN administration are usually performed by different
individuals. The creation and allocation of storage resources
involve communication between the server and the storage
administrator. This includes the server administrator determining
virtual host bus adapters (vHBAs) and associated host WWPNs to be
used for a virtual server. Further, the server administrator
determines the requirements for new storage resources. The server
administrator talks to the storage administrator to determine where
to allocate the new storage. The host WWPNs are handed over to the
storage administrator. The storage administrator performs the
configuration. The storage administrator determines the target
WWPNs and logical unit numbers (LUNs) on the storage side that are
to access the new storage.
[0031] The storage administrator hands over target WWPNs and LUNs
to the server administrator. The server administrator configures
target WWPNs and LUNs and validates the access.
[0032] Furthermore, the configuration may change--either
deliberately, or inadvertently. The server administrator then is to
detect this and to straighten out issues with the storage
administrator.
[0033] According to an embodiment of the invention, the system
allows the server administrator to create a request for new storage
resources, in particularly for a group of host WWPNs. This request
is based upon, e.g., storage access groups. The request is then
sent to the storage administrator. The system automatically
performs a discovery process for each host WWPN on each physical
adapter, waiting for the requested storage resources to become
available.
[0034] In one example, the system alerts the server administrator
when storage resources matching the storage request appear, based
upon host WWPNs.
[0035] The system updates the storage request, in one embodiment,
providing address information of new LUN(s): target WWPNs, as well
as LUN numbers, its size, and GUID.
[0036] The system provides a list of physical adapters providing
access.
[0037] The system periodically updates, in one embodiment, the
information by repeating the discovery process and informs the
server administrator in case of changes, e.g., access lost.
[0038] In one embodiment of the invention, the server administrator
picks a server with the ability to create vHBAs and performs a
discovery process through physical host bus adapters (HBAs) for
these vHBAs. The server administrator creates a group of
vHBAs/WWPNs, or picks an existing group of vHBAs on that server.
Then, the server administrator creates a storage request based upon
the group of vHBAs/WWPNs together with storage requirements. The
storage administrator receives the request and subsequently creates
FCP LUNs and provides access for vHBAs with zoning and/or LUN
masking.
[0039] The system automatically determines when the request has
been fulfilled by triggering the discovery through the HBAs (e.g.,
all HBAs) for the WWPNs of the request. The system remembers the
HBAs (e.g., all) with access to the LUNs. Then, the system notifies
the server administrator.
[0040] The server administrator defines, for instance, a virtual
server, and adds a group of vHBAs. The server administrator then
activates the virtual server and vHBAs.
[0041] The server administrator or the system may have a large
number of HBAs. Only some have access to the FCP LUNs. The server
administrator or the system may then easily select the right ones
based upon results from discovery.
[0042] In case of failures, or if SAN changes occur, advantages of
an embodiment of the invention prevail over the state of the art,
as in case of a failure of a physical path. The system monitors the
LUNs for a group of WWPNs and automatically determines changes. For
example, if access through one of the HBAs fails, or new paths
become available. The system alerts the server administrator. The
server administrator may then easily decide to move a vHBA to a
different HBA.
[0043] FIG. 1 depicts one example of an overview of a network based
data processing system 210 for storage access through virtual host
bus adapters 40, 42, 80, 82 according to an embodiment of the
invention. A physical server 10 is shown, running a plurality of
virtual servers 20, 22, 24 administrated by a hypervisor 14. The
physical server 10 includes a plurality of host bus adapters 30,
32, 34, 36, 38, 39 acting as physical network ports to several
storage area networks (SAN) 100, 102, 104, connected to the
physical server 10 and providing access to a plurality of storage
resources 110, 112, 114. The connection of the virtual server 20 to
the networks 102, 104 via the host bus adapters 34, 36, 38, 39 is
achieved by the hypervisor 14 providing virtual host bus adapters
40, 42 to virtual server 20. Virtual host bus adapters 80, 82
depict the view of these virtual host bus adapters 40, 42 from the
virtual server 20.
[0044] FIG. 2 depicts one example of an overview of an
implementation of an embodiment of the invention with a storage
resource facility 74 for managing virtual host bus adapters 40, 42,
80, 82. FIG. 2 serves for demonstrating how a management console 70
as some high level management function of the system 210 is used
for creating and providing access to a group of storage resources
110, 112, 114 for a virtual server 20 on a physical server 10,
comprising a virtual server management facility 72 as a management
server 72 and a storage request facility 74 as a management
instance 74. The virtual server management facility 72 allows for
managing virtual server definitions and activating, deactivating,
and migrating virtual servers 20, 22, 24. The storage request
facility 74 allows for managing virtual host bus adapters 40, 42,
80, 82, administrating world-wide unique port names WWPN1, WWPN2, .
. . , creating, activating and deactivating virtual host bus
adapters 40, 42, 80, 82. The virtual server 20, running on the
physical server 10 is managed by the virtual server management
facility 72.
[0045] The data processing system 210, shown in FIGS. 1 and 2,
comprises, for instance, one computer system 212 executing the
hypervisor 14, wherein host bus adapters 30, 32, 34, 36, 38, 39 on
the computer system 212 are, in one example, permanently
connectable to storage resources 110, 112, 114 in at least one
storage area network 100, 102, 104. The hypervisor 14 provides
virtual instances of the host bus adapters 30, 32, 34, 36, 38, 39
as virtual host bus adapters 40, 42, 80, 82 to one of the virtual
servers 20, 22, 24. A world-wide unique port number 144 (FIG. 5)
and a logical unit number 146 are used to access a storage volume
110, 112, 114. A GUID 138 is used to identify a storage volume 110,
112, 114.
[0046] In FIG. 2, the physical server 10 provides the ability to
create/delete vHBAs and manage WWPNs. The server 10 further
provides the ability to activate/shutdown/migrate virtual servers
20, 22, 24. It further comprises the discovery facility 50,
providing the ability to perform a discovery on a physical HBA for
a WWPN, independently, if it is in use, or not.
[0047] The management console 70 comprises the virtual server
management facility 72 in order to be able to
create/modify/delete/migrate virtual servers 20, 22, 24. Further,
the system comprises the storage request facility 74 (SRF), which
can be part of the management console 70.
[0048] If a user plans for new storage for the virtual server 20,
the user, according to an embodiment of the invention, defines a
storage request 76, 78 on the management console 70 and/or the
storage request facility 74, specifying the name, description, as
well as a group of vHBAs/WWPNs. The storage request facility 74 may
contact the virtual server management facility 72 to get either
existing, or new WWPNs. Further, the user defines, in one example,
a number and size of LUNs.
[0049] The storage request facility 74 periodically calls the
discovery facility 50 to perform discovery of all (or selected)
WWPNs on all (or selected) physical adapters. The discovery
facility 50 reports back results, including which storage resources
(including their size, GUID, WWPNs/LUNs) are found on which
adapter. The storage request facility 74 compares the results
against the storage requests 76, 78, concerning the number and size
of newly detected LUNs for WWPNs specified for a request. The
storage request facility 74 notifies the user, including adapters
that can be used for accessing the new LUNs.
[0050] In the embodiment shown in FIG. 2, the management server 72
comprises the management instance 74 for evaluating a possibility
of attaching storage resources 110, 112, 114 to virtual machine
instances 20, 22, 24 generated by the hypervisor 14. The management
instance 74 handles storage area network requests for a group 62
comprising at least one world-wide unique port number for virtual
host bus adapters 40, 42, 80, 82. In response of such a request, a
discovery is performed for each world-wide unique port number 130
in the group 62 on each host bus adapter 30, 32, 34, 36, 38, 39. A
discovery facility 50 is implemented on the computer system 212 for
performing the discovery process. The collected information is then
analyzed to determine the availability of the corresponding storage
resources 110, 112, 114.
[0051] The virtual server management facility 72 submits a request
to the management instance 74 on each startup of a virtual machine
instance 20, 22, 24 in order to optimize the selection of host bus
adapters 30, 32, 34, 36, 38, 39 for the virtual host bus adapters
40, 42, 80, 82 of the virtual machine instance 20, 22, 24. The
management instance 74 further analyzes the collected information
to also determine the best available host bus adapter 30, 32, 34,
36, 38, 39 in dependence of path quality criteria. Path quality
criteria include, as examples, path redundancy and/or utilization
of the host bus adapters 30, 32, 34, 36, 38, 39. The virtual server
management facility 72 informs the hypervisor 14 on which physical
host bus adapter a virtual host bus adapter is to be
instantiated.
[0052] The requests comprise, in one example, information on
storage requirements, in particular information on a number and
storage size of storage resources 110, 112, 114. The management
instance 74 automatically determines when the request has been
fulfilled. The management instance 74 triggers a discovery process
through the host bus adapters 30, 32, 34, 36, 38, 39 for the
virtual host bus adapters 80, 82 of the virtual machine instance
20, 22, 24. A request is submitted, in one example, to the
management instance 74 for a group 62 of virtual host bus adapters
40, 42, 80, 82. The management instance 74 alerts the hypervisor 14
in case all requirements of a request are fulfilled in the
discovery process.
[0053] A continuous monitoring process may be performed for
determining changes in an availability of storage volume 110, 112,
114. A request may be updated if information on new virtual host
bus adapters 40, 42, 80, 82 is provided to the management instance
74. Therefore, in one example, the discovery process is
periodically repeated for updating information on storage volume
110, 112, 114.
[0054] The request is submitted, in one example, to the management
instance 74 by the hypervisor 14 before a virtual machine instance
20, 22, 24 is generated by the hypervisor 14.
[0055] FIG. 3 depicts one example of a flow chart for operating a
computer system 212 for attaching storage resources 110, 112, 114
to virtual machine instances 20, 22, 24 according to an embodiment
of the invention.
[0056] Numeral references used in the descriptions of FIGS. 3 to 7
refer to FIGS. 1 and 2.
[0057] The method is implemented, in one embodiment, on a data
processing system 210 comprising one or more computer systems 212
executing at least one hypervisor 14 each. Host bus adapters 30,
32, 34, 36, 38, 39 on the computer system 212 are, e.g.,
permanently connectable to storage resources 110, 112, 114 in at
least one storage area network 100, 102, 104. The at least one
hypervisor 14 provides virtual instances of the host bus adapters
30, 32, 34, 36, 38, 39 as virtual host bus adapters 40, 42, 80, 82.
A world-wide unique port number 144 (FIG. 5) and a logical unit
number 146 are used to access a storage volume 110, 112, 114. A
GUID 138 is used to identify a storage volume 110, 112, 114.
[0058] The method comprises a management server 72 comprising a
management instance 74 evaluating a possibility of attaching
storage resources 110, 112, 114 to virtual machine instances 20,
22, 24 generated by the hypervisor 14. The management instance 74
handles storage area network requests for a group 62 comprising at
least one world-wide unique port number 130 for a virtual host bus
adapter 40, 42, 80, 82.
[0059] In response of such a request, a discovery is performed for
each world-wide unique port number 130 in the group 62 on each host
bus adapter 30, 32, 34, 36, 38, 39 corresponding to identifiers for
the virtual host bus adapters 40, 42, 80, 82 and the collected
information is then analyzed to determine the availability of the
corresponding storage resources 110, 112, 114.
[0060] The hypervisor 14 submits, in one example, a request to the
management instance 74 on each startup of a virtual machine
instance 20, 22, 24 in order to optimize the selection of host bus
adapters 30, 32, 34, 36, 38, 39 for the virtual host bus adapters
40, 42, 80, 82 of the virtual machine instance 20, 22, 24. The
management instance 74 further analyzes the collected information
to also determine the best available host bus adapter 30, 32, 34,
36, 38, 39 in dependence of path quality criteria. The path quality
criteria include, for instance, path redundancy and/or utilization
of the host bus adapters 30, 32, 34, 36, 38, 39.
[0061] The requests include, e.g., information on storage
requirements, in particular information on a number and storage
size of storage resources 110, 112, 114. The management instance 74
automatically determines, in one embodiment, when the request has
been fulfilled. The management instance 74 triggers a discovery
process through the host bus adapters 30, 32, 34, 36, 38, 39 for
the virtual host bus adapters 40, 42, 80, 82 of the virtual machine
instance 20, 22, 24.
[0062] According to an embodiment of the invention depicted in FIG.
3, the user defines a request to a storage administrator via the
storage request facility 74 in step S300. Next, in step S302, the
storage request facility 74 remembers the request. In step S304,
the storage request facility 74 starts the discovery process for
the host world-wide unique port names (WWPNs) 130 through all (or
selected) available host bus adapters (HBAs) 30, 32, 34, 36, 38,
39. Next, in step S306, the storage administrator picks a storage
subsystem, creates logical unit numbers (LUNs) 146, performs LUN
masking and zoning. In step S308, the storage request facility 74
checks the results of the discovery process. Then, in step S310, it
is checked if any storage request 76, 78 is fulfilled. If this is
not the case, the process returns to step S304 for restarting the
discovery process. If the storage request 76, 78 is fulfilled, then
the storage request facility 74 in step S312 tells the server
administrator that the request is fulfilled and provides a list of
host bus adapters 30, 32, 34, 36, 38, 39 that may be used.
Optionally, in the step S314, the virtual server management
facility 72 may automatically configure the virtual host bus
adapters 40, 42, 80, 82.
[0063] FIG. 4 depicts one example of a flow chart for the discovery
process according to an embodiment of the invention. In step S400,
a storage request list 122 (FIG. 5) contains a list of all (or
selected) WWPN 130 to be discovered. The storage request list 122
contains an entry for each requested LUN, attributed with a LUN
size 136, and a status 140, marked with "requested". The storage
request facility 74 creates a port discovery list 120 with all (or
selected) host bus adapters 126 (1010, 1020, . . . ), as depicted
in FIG. 5. For each host bus adapter 126, attributed to a storage
area network 128 (1, 2, . . . ), a list of the world-wide unique
port names 130 (WWPN1, WWPN2, . . . ) to be discovered is created.
These world-wide unique port names 130 are used for all (or
selected) storage requests 76, 78. In the port discovery list it is
marked with "y" if the discovery process is successful.
[0064] If two or more physical ports connect to the same SAN, in
one example, a world-wide unique port name 130 is only added to one
of the physical ports for discovery. This avoids a SAN from logging
out a potentially existing login of a world-wide unique port name
130, and avoids unnecessary discovery.
[0065] Next, in step S402 (FIG. 4), it is checked if the discovery
is done on each host bus adapter 126 according to the host bus
adapters 30, 32, 34, 36, 38, 39 of the embodiment depicted in FIGS.
1 and 2. If this is not the case, in step S408, a discovery is
performed for each host WWPN 130 on the next host bus adapter 126.
Then, a result of the discovery process for the host bus adapters
126 is collected in step S410. Corresponding tables are shown in
FIG. 5 as a storage request list 122 and a LUN list 124. If a
logical unit number 146 is found for a host WWPN 130, the host bus
adapter port 126, as well as the LUN GUID 138 plus its target WWPN
144, and the LUN size 136 are added to the LUN list 124 for the
host WWPN 130.
[0066] Accordingly, in the storage request list 122 if an entry
exists for a LUN with a matching GUID 138, the status 140 is set to
"found", and the LUN size 136 is updated. If no entry exists with a
matching GUID, but an entry with a matching LUN size 136 and a
status 140 set to "requested" exists, the status 140 is set to
"found", and the GUID 138 is set to the GUID of the discovered
LUN.
[0067] Having accomplished step S410 the flow continues with the
check in step S402 for the discovery process done on each host bus
adapter 30, 32, 34, 36, 38, 39. Then, if each storage request 76,
78 is checked (step S404), it is checked in step S406 if all
requests are fulfilled. If this is the case, the discovery process
is ended. If not all requests are fulfilled, the discovery process
is restarted at the beginning with step S400.
[0068] If in step S404 not each storage request 76, 78 is checked,
in step S412, the results of the discovery process are checked for
each host WWPN 130 of the storage request 76, 78. Then, in step
S414, if the number of LUNs plus their size found matches the
storage request 76, 78, the server administrator is notified in
step S416 that the request has been fulfilled. If the check in step
S414 is negative, the flow continues with the step S404, if each
storage request 76, 78 is fulfilled.
[0069] FIG. 6 depicts one example of a flow chart for a continuous
monitoring process according to an embodiment of the invention. The
monitoring process starts in step S600 by the storage request
facility 74 setting the "confirmed" field 148 of each LUN list 124
as depicted in FIG. 7 to "no". Next, in step S602, the storage
request facility 74 creates a list with all (or selected) host bus
adapter ports 126. For each host bus adapter port 126, a list of
the host WWPNs 130 is to be discovered. These are the WWPNs 130 of
all previous storage requests 76, 78. Then, in step S604, it is
checked if the discovery process is done on each host bus adapter
126. If this is the case, it is checked in step S606 if each
storage request 76, 78 is checked. If this is the case, the
monitoring process is accomplished.
[0070] If the check on discovery done on each host bus adapter 126
in step S604 is negative, in step S608 a discovery is performed for
each host WWPN 130 on the next host bus adapter 126. The result of
the discovery process is collected in step S610 for the host bus
adapter 126. If LUNs 146 are found, the "confirmed" field in the
LUN list 124 is updated. Then, the flow is continued with step S604
with the check on the discovery done on each host bus adapter
126.
[0071] The port discovery list 120, as well as the storage request
list 122 and the LUN list 124 depicted in FIG. 7 for the monitoring
process are resembling the lists shown in FIG. 5 for the discovery
process. The only difference is the "confirmed" field 148 of the
LUN list 124.
[0072] If the check in step S606, if each storage request 76, 78 is
checked, is negative, the results of the discovery process for each
host WWPN 130 of the storage request 76, 78 are checked in step
S612. Next, in step S614, it is checked if any of the host WWPNs
130 cannot access all LUNs 146. If the answer is negative, the flow
continues with step S606 again. If the answer is positive, the
server administrator is notified in step S616 that there is an
issue with these host WWPNs 130. With this notification, the list
of the host bus adapters 126 that can be used alternatively is
included. Then, the monitoring process is finished.
[0073] Referring now to FIG. 8, a schematic of an example of a data
processing system 210 is shown. Data processing system 210 is only
one example of a suitable data processing system and is not
intended to suggest any limitation as to the scope of use or
functionality of embodiments of the invention described herein.
Regardless, data processing system 210 is capable of being
implemented and/or performing any of the functionality set forth
herein above.
[0074] Computer system/server 212 may be described in the general
context of computer system executable instructions, such as program
modules, being executed by a computer system. Generally, program
modules may include routines, programs, objects, components, logic,
data structures, and so on that perform particular tasks or
implement particular abstract data types. Computer system/server
212 may be practiced in distributed cloud computing environments
where tasks are performed by remote processing devices that are
linked through a communications network. In a distributed cloud
computing environment, program modules may be located in both local
and remote computer system storage media including memory storage
devices.
[0075] As shown in FIG. 8, computer system/server 212 in data
processing system 210 is shown in the form of a general-purpose
computing device. The components of computer system/server 212 may
include, but are not limited to, one or more processors or
processing units 216, a system memory 228, and a bus 218 that
couples various system components including system memory 228 to
processor 216.
[0076] Bus 218 represents one or more of any of several types of
bus structures, including a memory bus or memory controller, a
peripheral bus, an accelerated graphics port, and a processor or
local bus using any of a variety of bus architectures. By way of
example, and not limitation, such architectures include Industry
Standard Architecture (ISA) bus, Micro Channel Architecture (MCA)
bus, Enhanced ISA (EISA) bus, Video Electronics Standards
Association (VESA) local bus, and Peripheral Component Interconnect
(PCI) bus.
[0077] Computer system/server 212 typically includes a variety of
computer system readable media. Such media may be any available
media that is accessible by computer system/server 212, and it
includes both volatile and non-volatile media, removable and
non-removable media.
[0078] System memory 228 can include computer system readable media
in the form of volatile memory, such as random access memory (RAM)
230 and/or cache memory 232. Computer system/server 212 may further
include other removable/non-removable, volatile/non-volatile
computer system storage media. By way of example only, storage
system 234 can be provided for reading from and writing to a
non-removable, non-volatile magnetic media (not shown and typically
called a "hard drive"). Although not shown, a magnetic disk drive
for reading from and writing to a removable, non-volatile magnetic
disk (e.g., a "floppy disk"), and an optical disk drive for reading
from or writing to a removable, non-volatile optical disk such as a
CD-ROM, DVD-ROM or other optical media can be provided. In such
instances, each can be connected to bus 218 by one or more data
media interfaces. As will be further depicted and described below,
memory 228 may include at least one program product having a set
(e.g., at least one) of program modules that are configured to
carry out the functions of embodiments of the invention.
[0079] Program/utility 240, having a set (at least one) of program
modules 242, may be stored in memory 228 by way of example, and not
limitation, as well as an Operating System, one or more application
programs, other program modules, and program data. Each of the
Operating System, one or more application programs, other program
modules, and program data or some combination thereof, may include
an implementation of a networking environment. Program modules 242
generally carry out the functions and/or methodologies of
embodiments of the invention as described herein.
[0080] Computer system/server 212 may also communicate with one or
more external devices 214 such as a keyboard, a pointing device, a
display 224, etc.; one or more devices that enable a user to
interact with computer system/server 212; and/or any devices (e.g.,
network card, modem, etc.) that enable computer system/server 212
to communicate with one or more other computing devices. Such
communication can occur via Input/Output (I/O) interfaces 222.
Still yet, computer system/server 212 can communicate with one or
more networks such as a local area network (LAN), a general wide
area network (WAN), and/or a public network (e.g., the Internet)
via network adapter 220. As depicted, network adapter 220
communicates with the other components of computer system/server
212 via bus 218. It should be understood that although not shown,
other hardware and/or software components could be used in
conjunction with computer system/server 212. Examples, include, but
are not limited to: microcode, device drivers, redundant processing
units, external disk drive arrays, RAID systems, tape drives, and
data archival storage systems, etc.
[0081] In one aspect, a data processing system is provided that
includes one or more computer systems executing at least one
hypervisor each. Host bus adapters on the computer system are
permanently connectable to storage resources in at least one
storage area network. The at least one hypervisor provides virtual
instances of the host bus adapters as virtual host bus adapters,
and a world-wide unique port number and a logical unit number are
used to access a storage volume. The storage volume is identified,
for instance, by its globally unique identifier. The data
processing system is characterized by a management server
comprising a management instance for evaluating a possibility of
attaching storage resources to virtual machine instances generated
by the hypervisor. The management instance handles storage area
network requests for a group comprising at least one world-wide
unique port number for a virtual host bus adapter. In response of
such a request, a discovery is performed for each world-wide unique
port number in the group on each host bus adapter and the collected
information is then analyzed to determine the availability of the
corresponding storage resources.
[0082] As one example, the storage volume is identified by its
globally unique identifier (GUID), as defined by IEEE T10 and T11
standards committees.
[0083] In one embodiment, a hypervisor allows the assignment of a
virtual host bus adapter to a physical host bus adapter port. A
request is sent over a virtual host bus adapter, which is
attributed to a host WWPN. Thus, the first WWPN of a request is
implicitly given. It determines access permissions in the network,
and on the storage subsystem, which is providing storage
resources.
[0084] In a further aspect, a method is provided for attaching
storage resources to virtual machine instances of a data processing
system. The data processing system includes one or more computer
systems executing at least one hypervisor each. Host bus adapters
on a computer system are permanently connectable to storage
resources in at least one storage area network. The at least one
hypervisor provides virtual instances of the host bus adapters as
virtual host bus adapters. A world-wide unique port number and a
logical unit number are used to access a storage volume. The
storage volume is identified, in one example, by its globally
unique identifier. The method includes, for instance, a management
server comprising a management instance evaluating a possibility of
attaching storage resources to virtual machine instances generated
by the hypervisor. The management instance handles storage area
network requests for a group comprising at least one world-wide
unique port number for a virtual host bus adapter. In response of
such a request, a discovery is performed for each world-wide unique
port number in the group on each host bus adapter for virtual host
bus adapters and the collected information is then analyzed to
determine the availability of the corresponding storage
resources.
[0085] One or more aspects of the invention relate to a virtualized
environment with a computer system or computer platforms connected
to storage area networks (SAN), providing a hypervisor with support
for virtual servers and Fibre Channel Protocol (FCP) storage for
disk I/O processes.
[0086] According to one aspect, a request (WWPNs, number of new
storage resources, including their expected size) is created for
new storage resources for a group of virtual host bus adapters
(vHBAs). The request is triggering the fulfillment evaluation by
doing a continuous monitoring of the available storage resources
for these vHBAs and by performing a discovery on each physical
adapter for each WWPN. The result of the discovery is analyzed to
determine if the sensed results can fulfill the request.
[0087] According to one aspect, a request (WWPNs, GUIDs of known
storage resources) is created for known storage resources for a
group of virtual host bus adapters (vHBAs). The request is
triggering the evaluation of the availability of the storage
resources for these vHBAs by performing a discovery on each
physical adapter for each WWPN. The result of the discovery is
analyzed through which ports and vHBAs the known storage resources
can be accessed.
[0088] Thus, in one embodiment, two types of requests are
described: a request for fulfillment where a storage administrator
creates new storage resources and a monitoring/re-validation of
already known storage resources.
[0089] In one embodiment, these steps are performed before the
virtual server using the vHBAs is started or even available. This
is possible because the adapter code provides an entry point to
issue a discovery and so the paths to the storage resources can be
discovered. This enables also the optimization of the configuration
of storage resources for each virtual server at each startup by
analyzing the path quality (path redundancy, utilization, . . . )
results of the performed discovery. It also enables a system wide
continuous monitoring and so error indication in case storage
resources are no longer reachable by storing the previous discovery
result and comparing it to the current result.
[0090] Thus, one or more aspects support eliminating the dependency
between system and SAN configuration, concerning, e.g.,
adding/removing virtual servers, adding/removing host bus adapters
(HBAs), planning for virtual server migration, adding/removing, or
sharing storage resources. Further, one or more aspects support the
management of systems comprising a large number of virtual host bus
adapters (vHBAs), exhibiting 16 hex digit WWPNs, as well as the
server administration for the creation, assigning and managing of
individual vHBAs. Further, one or more aspects exhibit advantages
where separate management domains (server and SAN) exist and, for
instance, where a server configuration only partly reflects a SAN
configuration.
[0091] In one or more aspects, the user only has to specify a group
of virtual servers, and host bus adapters. The system creates
vHBAs/WWPNs, on different servers, if required. This action is
taken independently of a virtual server, which means activation of
a vHBA's, e.g., undertaken independently of a virtual server. That
is, vHBA connectivity can be validated on a physical server which
is only a potential target for a virtual server migration. The
virtual server only describes, for instance, requirements towards
the storage resources that are to be accessed. The system picks and
assigns a vHBA as the virtual server requires it. vHBAs are managed
as a group, not as individual vHBAs. They reflect the SAN
configuration and it allows the system to validate that a group of
vHBAs indeed has access to the same group of storage resources.
This is much more convenient than having the administrator
implicitly and/or manually group vHBAs and validate access.
[0092] In one or more aspects, only minor input from a server
administrator is used to create and manage vHBAs for virtual
servers. One basis of the method exhibits a group of storage
resources and virtual servers, where there is to be access to a
network or network resources, and HBAs are used to access the
network resources. A group of vHBAs is created for the group of
storage resources, instead of having an administrator to create
them individually as in the state of the art. vHBAs are managed as
a group. Information is added to the group of vHBAs that allows
relating server and SAN configuration.
[0093] In a further aspect, a computer program product is provided
for attaching storage resources to virtual machine instances. A
data processing system includes one or more computer systems
executing at least one hypervisor each. Host bus adapters on the
computer system are permanently connectable to storage resources in
at least one storage area network. The at least one hypervisor
provides virtual instances of the host bus adapters as virtual host
bus adapters. A world-wide unique port number and a logical unit
number are used to access a storage volume. The storage volume is
identified, in one example, by its globally unique identifier (as
defined by IEEE T10 and T11 standards committees). The computer
program product includes a computer readable storage medium having
program instructions embodied therewith. The program instructions
are executable by a computer to cause the computer to perform a
method including a management server including a management
instance evaluating a possibility of attaching storage resources to
virtual machine instances generated by the hypervisor. The
management instance handles storage area network requests for a
group comprising at least one world-wide unique port for a virtual
host bus adapter. In response of such a request, a discovery is
performed for each world-wide unique port number in the group on
each host bus adapter for virtual host bus adapters and the
collected information is then analyzed to determine the
availability of the corresponding storage resources.
[0094] Aspects of the present invention may be a system, a method,
and/or a computer program product at any possible technical detail
level of integration. The computer program product may include a
computer readable storage medium (or media) having computer
readable program instructions thereon for causing a processor to
carry out aspects of the present invention.
[0095] The computer readable storage medium can be a tangible
device that can retain and store instructions for use by an
instruction execution device. The computer readable storage medium
may be, for example, but is not limited to, an electronic storage
device, a magnetic storage device, an optical storage device, an
electromagnetic storage device, a semiconductor storage device, or
any suitable combination of the foregoing. A non-exhaustive list of
more specific examples of the computer readable storage medium
includes the following: a portable computer diskette, a hard disk,
a random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM or Flash memory), a static
random access memory (SRAM), a portable compact disc read-only
memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a
floppy disk, a mechanically encoded device such as punch-cards or
raised structures in a groove having instructions recorded thereon,
and any suitable combination of the foregoing. A computer readable
storage medium, as used herein, is not to be construed as being
transitory signals per se, such as radio waves or other freely
propagating electromagnetic waves, electromagnetic waves
propagating through a waveguide or other transmission media (e.g.,
light pulses passing through a fiber-optic cable), or electrical
signals transmitted through a wire.
[0096] Computer readable program instructions described herein can
be downloaded to respective computing/processing devices from a
computer readable storage medium or to an external computer or
external storage device via a network, for example, the Internet, a
local area network, a wide area network and/or a wireless network.
The network may comprise copper transmission cables, optical
transmission fibers, wireless transmission, routers, firewalls,
switches, gateway computers and/or edge servers. A network adapter
card or network interface in each computing/processing device
receives computer readable program instructions from the network
and forwards the computer readable program instructions for storage
in a computer readable storage medium within the respective
computing/processing device.
[0097] Computer readable program instructions for carrying out
operations of the present invention may be assembler instructions,
instruction-set-architecture (ISA) instructions, machine
instructions, machine dependent instructions, microcode, firmware
instructions, state-setting data, configuration data for integrated
circuitry, or either source code or object code written in any
combination of one or more programming languages, including an
object oriented programming language such as Smalltalk, C++, or the
like, and procedural programming languages, such as the "C"
programming language or similar programming languages. The computer
readable program instructions may execute entirely on the user's
computer, partly on the user's computer, as a stand-alone software
package, partly on the user's computer and partly on a remote
computer or entirely on the remote computer or server. In the
latter scenario, the remote computer may be connected to the user's
computer through any type of network, including a local area
network (LAN) or a wide area network (WAN), or the connection may
be made to an external computer (for example, through the Internet
using an Internet Service Provider). In some embodiments,
electronic circuitry including, for example, programmable logic
circuitry, field-programmable gate arrays (FPGA), or programmable
logic arrays (PLA) may execute the computer readable program
instructions by utilizing state information of the computer
readable program instructions to personalize the electronic
circuitry, in order to perform aspects of the present
invention.
[0098] Aspects of the present invention are described herein with
reference to flowchart illustrations and/or block diagrams of
methods, apparatus (systems), and computer program products
according to embodiments of the invention. It will be understood
that each block of the flowchart illustrations and/or block
diagrams, and combinations of blocks in the flowchart illustrations
and/or block diagrams, can be implemented by computer readable
program instructions.
[0099] These computer readable program instructions may be provided
to a processor of a general purpose computer, special purpose
computer, or other programmable data processing apparatus to
produce a machine, such that the instructions, which execute via
the processor of the computer or other programmable data processing
apparatus, create means for implementing the functions/acts
specified in the flowchart and/or block diagram block or blocks.
These computer readable program instructions may also be stored in
a computer readable storage medium that can direct a computer, a
programmable data processing apparatus, and/or other devices to
function in a particular manner, such that the computer readable
storage medium having instructions stored therein comprises an
article of manufacture including instructions which implement
aspects of the function/act specified in the flowchart and/or block
diagram block or blocks.
[0100] The computer readable program instructions may also be
loaded onto a computer, other programmable data processing
apparatus, or other device to cause a series of operational steps
to be performed on the computer, other programmable apparatus or
other device to produce a computer implemented process, such that
the instructions which execute on the computer, other programmable
apparatus, or other device implement the functions/acts specified
in the flowchart and/or block diagram block or blocks.
[0101] The flowchart and block diagrams in the Figures illustrate
the architecture, functionality, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments of the present invention. In this
regard, each block in the flowchart or block diagrams may represent
a module, segment, or portion of instructions, which comprises one
or more executable instructions for implementing the specified
logical function(s). In some alternative implementations, the
functions noted in the block may occur out of the order noted in
the Figures. For example, two blocks shown in succession may, in
fact, be executed substantially concurrently, or the blocks may
sometimes be executed in the reverse order, depending upon the
functionality involved. It will also be noted that each block of
the block diagrams and/or flowchart illustration, and combinations
of blocks in the block diagrams and/or flowchart illustration, can
be implemented by special purpose hardware-based systems that
perform the specified functions or acts or carry out combinations
of special purpose hardware and computer instructions.
[0102] Further, other types of computing environments can benefit
and be used. As an example, a data processing system suitable for
storing and/or executing program code is usable that includes at
least two processors coupled directly or indirectly to memory
elements through a system bus. The memory elements include, for
instance, local memory employed during actual execution of the
program code, bulk storage, and cache memory which provide
temporary storage of at least some program code in order to reduce
the number of times code must be retrieved from bulk storage during
execution.
[0103] Input/Output or I/O devices (including, but not limited to,
keyboards, displays, pointing devices, DASD, tape, CDs, DVDs, thumb
drives and other memory media, etc.) can be coupled to the system
either directly or through intervening I/O controllers. Network
adapters may also be coupled to the system to enable the data
processing system to become coupled to other data processing
systems or remote printers or storage devices through intervening
private or public networks. Modems, cable modems, and Ethernet
cards are just a few of the available types of network
adapters.
[0104] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising", when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components and/or groups thereof.
[0105] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below, if any, are intended to include any structure,
material, or act for performing the function in combination with
other claimed elements as specifically claimed. The description of
one or more embodiments has been presented for purposes of
illustration and description, but is not intended to be exhaustive
or limited to in the form disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art.
The embodiment was chosen and described in order to best explain
various aspects and the practical application, and to enable others
of ordinary skill in the art to understand various embodiments with
various modifications as are suited to the particular use
contemplated.
* * * * *